Just wanted the Appointments Plugin

I just wanted to get the membership for one plugin and for some reason it will not let me update it on my site. It will be going on dermspecialistsofhouston.com but right now for testing I have it on yourwebsitedesignnow.com. I'm not sure why it keeps asking me to upgrade. I just want access to the one plugin can we somehow switch my membership to that plugin and let me know how I can get access to upgrades for it? Thanks